Become a Member

Get access to more than 30 brands, premium video, exclusive content, events, mapping, and more.

Already have an account? Sign In

Become a Member

Get access to more than 30 brands, premium video, exclusive content, events, mapping, and more.

Already have an account? Sign In


Weight Loss

Are These Chemicals Making You Fat?

Chemicals that cause weight gain - and prevent you from losing weight - lurk in food, water and the environment. Here's how to identify and avoid them for easier weight loss.

Get access to everything we publish when you sign up for Outside+.

If losing weight were really as simple as eating less and exercising more, we’d all be lean. But new research suggests the calories-in-calories-out formula doesn’t always work: chemicals that cause weight gain are everywhere. They lurk in food, water and the environment and can promote weight gain and fat storage, regardless of how little you eat or how much you work out.

The chemicals that cause weight gain are called obesogens—hormones and pesticides in conventional meat and produce, plastic packaging, additives in processed foods, and even household cleaners. Most have endocrine-disrupting effects, mimicking the body’s natural hormones and interfering with normal hormone production in a way that encourages weight gain and fat storage. These fat chemicals have been shown to promote insulin resistance, trigger inflammation and oxidative stress, impact thyroid metabolism, disrupt appetite regulation, damage the mitochondria (the cell’s energy producers) and trigger cells to become fat cells. Research also suggests these “chemical calories” may be more relevant to weight loss than energy calories. Dozens of studies link obesogen exposure with weight gain, fat storage and obesity. And endocrine disruptors also increase the risk of cancer, reproductive problems, immune and respiratory issues, and other serious conditions.

But it’s not as simple as eating organic or going vegan. Conventional apples or lettuce, for example, may contain more endocrine-disrupting compounds than organic, pasture-raised burgers. And the organic beans you’re buying may be packed in cans linked with bisphenol A (BPA), which is a powerful endocrine-disrupting compound that prompts your body to store fat. 

Lessen your exposure, help rid your body of fat-promoting toxins, support your weight-loss routine and reduce your risk of disease with these simple strategies:

1. Up your vegetables

Broccoli, kale and other crucifers are rich in phytochemicals that minimize the impact of estrogenic compounds. Same with onions, garlic, berries and other fruits and vegetables. Conventional produce is high in endocrine-disrupting pesticides and fungicides—but if going totally organic is beyond your budget, avoiding the most heavily-treated produce can lessen your pesticide exposure by as much as 80 percent. Always choose organic versions of these: strawberries, kale and leafy greens, nectarines, apples, grapes, cherries, peaches, pears, peppers, celery and tomatoes. For more information, check out the Environmental Working Group’s “Dirty Dozen” checklist.

2. Stop using plastic

Cling wrap, plastic juice bottles, food storage containers, take-out boxes, even shower curtains are among the most common sources of endocrine-disrupting chemicals that prompt your body to store fat. Kick that plastic to the curb: use Pyrex or bamboo containers for food storage, choose restaurants that package take-out in compostable containers, and swap your plastic shower curtain for fabric.

3. Sweat it out

Steam rooms, saunas and other heat therapies promote perspiration to speed the removal of toxins and some research shows sauna therapy can enhance the body’s excretion of lead, mercury and other heavy metals, as well as fat-soluble toxins like PCBs.

4. Kick the cans

Your organic chickpeas and coconut milk are probably packed in a can lined with BPA; even cans marked as “BPA-free” may be lined with other endocrine-disrupting chemicals that cause weight gain. Kick the cans: cook dried beans from scratch, use frozen vegetables in bags and buy tomato sauce and other canned goods in glass jars. In addition to that, make your own coconut milk (it’s easy): puree unsweetened coconut with filtered water, then strain through cheesecloth or a nut milk bag.

5. Eat the right meat

Conventionally grown beef, poultry and pork are laced with both natural and synthetic hormones and steroids, linked with weight gain and obesity. But those veggie burgers may not be the best option. Most contain soy protein, high in naturally occurring estrogenic compounds that can prompt the formation of fat cells, and other additives. If you eat meat, choose organic, grass-fed and/or pastured varieties that haven’t been treated with added hormones. And use meat substitutes as an occasional treat, not every day fare.

6. Filter (all) your water

Tap water contains pesticides, drug residues, fluoride and other toxins, and some research shows drinking water is a significant route of exposure to endocrine-disrupting chemicals. Invest in a high-quality under-sink filter that removes a variety of contaminants. And because many toxins may be absorbed through the skin, install a filter in your bath or shower, or consider a whole-home filtration system.

7. BYO bottle

Plastic water bottles are one of the most common sources of BPA, and Styrofoam cups contain styrene, an endocrine-disruptor linked with cancer. Skip the Styrofoam, and carry a stainless or ceramic coffee cup for hot beverage refills on the go. And don’t be fooled by “BPA-free” water bottles; new studies suggest most plastics release estrogenic chemicals that cause weight gain, even if they don’t contain BPA. Get an unlined stainless steel water bottle, and fill it at home from your filtered water.

8. Be wary of dairy

Conventional dairy usually contains pesticides and added hormones, and one review of research from 10 different universities linked hormones in dairy cows with an increased risk of obesity. Even untreated milk, cheese and yogurt are high in naturally occurring estrogens that can interfere with your body’s own system. But plant-based options aren’t always better: milk and yogurt made from soy contain naturally estrogenic phytochemicals. If you do eat dairy, choose only organic versions from pasture-raised animals not treated with added hormones. And stick to plant-based milk or yogurt made from nuts, seeds or coconut, instead of soy.

9. Restock your pantry

Processed, packaged foods are likely to be laced with a wide variety of obesogenic compounds, including pesticides and high-fructose corn syrup (HFCS), shown to impact hormones that play a role in appetite regulation and promote fat storage. And microwave popcorn contains PFOA (perfluorooctanoic acid), an endocrine-disrupting chemical also linked with tumor growth. Toss processed foods, and restock with dried beans, grains and organic, clean treats. And when you check out at the store, skip the receipt; many contain high levels of BPA, which can transfer through your skin.

10. Be selective with seafood

Fish and seafood, especially tuna, mackerel and swordfish, are high in endocrine-disrupting heavy metals like mercury and lead. Similarly, farm-raised fish are likely to contain pesticide residues, antibiotics and other fat-promoting chemicals that cause weight gain (not to mention, canned tuna is usually packed in BPA-lined containers). Be safe with seafood: sardines, crab, catfish, flounder, haddock and anchovies are lower in mercury and other toxins. And choose wild-caught or responsibly farmed varieties; check out Aquaculture Stewardship Council for a list of the cleanest choices.

11. Clean your house

Conventional soaps, laundry detergents, dryer sheets and household cleaners are high in obesogenic compounds, and most are scented with chemical fragrances that contain endocrine-disrupting phthalates. The same goes for scented personal care products (plus, many contain paraben, an endocrine-disrupting preservatives). Choose natural, plant-based and/or organic household cleaners and personal care products free from parabens and chemicals, and scented only with pure essential oils.

12. Support with supplements

Help rid your body of stored obesogens and heal damage, with science-backed supplements.  Some to try: curcumin, black radish, N–acetyl-cysteine (NAC), Oregon grape root, garlic extract and dandelion root have all been shown to promote chemical detox, while protecting against the inflammation, oxidative stress and cellular damage caused by toxins.

Now that you’ve rid your diet and environment of chemicals that cause weight gain, here are some other helpful articles to help you lose weight effectively and healthily: